A gin-pole derrick comprises a mast having guys secured to its lower end and arranged to permit the mast to lean in any desired inclination relative to ground level. A load may be raised or lowered by ropes leading through sheaves or blocks, also secured to the upper end of the mast. The lower end of the mast is normally attached to a support bracket by a removable pivot pin.
A common problem with this type of connector for a conventional gin-pole derrick is that the pin is oftentimes lost upon removal thereof for purposes of replacing the mast. One solution to such problems may be found in U.S. Pat. No. 3,847,488 wherein a threaded bolt is adapted to remain attached to a pair of support brackets upon removal of the mast therefrom. However, problems arise with the latter type of connector, such as the accumulation of dirt and the like in the exposed threads of the bolt which render it difficult to function properly over an extended period of time.